There is growing interest in the use of context-awareness as a technique for developing pervasive computing applications that are flexible, adaptable, and capable of acting autonomously on behalf of users. However, context-awareness introduces various software engineering challenges, as well as privacy and usability concerns. In this paper, we present a conceptual framework and software infrastructure that together address known software engineering challenges, and enable further practical exploration of social and usability issues by facilitating the prototyping and fine-tuning of context-aware applications.

Abstract. Context-awareness is a key concept in ubiquitous computing. But to avoid developing dedicated context-awareness sub-systems for specific application areas there is a need for more generic programming frameworks. Such frameworks can help the programmer to develop and deploy context-aware applications faster. This paper describes the Java Context-Awareness Framework – JCAF, which is a Java-based context-awareness infrastructure and programming API for creating context-aware computer applications. The paper presents the design principles behind JCAF, its runtime architecture, and its programming API. The paper presents some applications of using JCAF in three different applications and discusses lessons learned from using JCAF. 1

Most recently developed context-aware software applications make unrealistic assumptions about the quality of the available context information, which can lead to inappropriate actions by the application and frustration on the part of the user. In this paper, we explore the problem of imperfect context information and some of its causes, and propose a novel approach for modelling incomplete and inaccurate information. Additionally, we present a discussion of our experiences in developing a contextaware communication application, highlighting design issues that are pertinent when developing applications that rely on imperfect context information.

There is growing interest in the use of context-awareness as a technique for developing pervasive computing applications that are flexible, adaptable, and capable of acting autonomously on behalf of users. However, context-awareness introduces a variety of software engineering challenges. In this paper, we address these challenges by proposing a set of conceptual models designed to support the software engineering process, including context modelling techniques, a preference model for representing context-dependent requirements, and two programming models. We also present a software infrastructure and software engineering process that can be used in conjunction with our models. Finally, we discuss a case study that demonstrates the strengths of our models and software engineering approach with respect to a set of software quality metrics.

Context-aware, multi-channel Web applications are more and more gaining consensus among both content providers and consumers, but very few proposals exist for their conceptual modeling. This paper illustrates a conceptual framework that provides modeling facilities for context-aware, multi-channel Web applications; it also shows how high-level modeling constructs can drive the application development process through automatic code generation. Our work stresses the importance of user-independent, context-triggered adaptation actions, in which the context plays the role of a “first class ” actor, operating independently from users on the same hypertext the users navigate. Modeling concepts are based on WebML (Web Modeling Language), an already established conceptual model for data-intensive Web applications, which is also accompanied by a development method and a CASE tool. However, given their general validity, the concepts of this paper shape up a complete framework that can be adopted independently from the chosen model, method, and tool.

Today the computer is changing from a big, grey, and noisy thing on our desk to a small, portable, and ever-networked item most of us are carrying around. This new found mobility imposes a shift in how we view computers and the way we work with them. When interaction can occur anywhere at any time it is imperative that the system adapts to the user in whatever situation the user is in. To facilitate this adaptivity we propose a two tier architecture. A middleware layer implementing a general mechanism for aggregating and maintaining contextual information. The second part offers automatic situation assessment through Case-Based Reasoning. We demonstrate a multi-agent system for supplying context-sensitive services in a mobile environment.

Building of context-aware applications in pervasive computing environments faces the difficult problem of dealing with uncertain context information. In this paper, we propose a probability extension to our ontology-based model for representing uncertain contexts; and use Bayesian networks to reason about uncertainty. In addition, the supports of probabilistic markups and Bayesian networks have been incorporated into our contextaware middleware system to enable the building of context-aware services by using various uncertain contexts. We also present our experiences and discussions.

Pervasive computing applications must be engineered to provide unprecedented levels of flexibility in order to reconfigure and adapt in response to changes in computing resources and user requirements. To meet these challenges, appropriate software engineering abstractions and infrastructure are required as a platform on which to build adaptive applications. In this paper, we demonstrate the use of a disciplined, model-based approach to engineer a context-aware, Session Initiation Protocol (SIP) based communication application. This disciplined approach builds on our previously developed conceptual models and infrastructural components, which enable the description, acquisition, management and exploitation of arbitrary types of context and user preference information to enable adaptation to context changes.

Development of context-aware applications is inherently complex. These applications adapt to changing context information: physical context, computational context, and user context/tasks. Context information is gathered from a variety of sources that differ in the quality of information they produce and that are often failure prone. The pervasive computing community increasingly understands that developing context-aware applications should be supported by adequate context information modelling and reasoning techniques. These techniques reduce the complexity of context-aware applications and improve their maintainability and evolvability. In this paper we discuss the requirements that context modelling and reasoning techniques should meet, including the modelling of a variety of context information types and their relationships, of situations as abstractions of context information facts, of histories of context information, and of uncertainty of context information. This discussion is followed by a description and comparison of current context modelling and reasoning techniques.

Abstract. More and more Web users ask for contents and services highly tailored to their particular contexts of use. Especially due to the increasing affordability of new and powerful mobile communication devices, they also appreciate the availability of ubiquitous access, independent from the device actually in use. Due to such premises, traditional software design methods need to be extended, and new issues and requirements need to be addressed for supporting context-aware access to services and applications. In this paper we propose a model-driven approach towards adaptive, context-aware Web applications, accompanied by a general-purpose execution framework enabling active context-awareness. Whereas conventional adaptive hypermedia systems address the problem of adapting HTML pages in response to user-generated requests, in this work we especially stress the importance of user-independent, context-triggered adaptivity actions. This finally leads us to interpret the context as an active actor, operating independently from users during their navigations. 1